Pump assembly



H. E. ADAMS PUMP ASSEMBLY March E4, E95@ 3 Sheets-Sheet 1 Filed Sept. 19, 1945 Mam}?! 3% H. E. ADAMS 25%32 4 PUMP ASSEMBLY Filed Sept. 19, 1945 3 Sheets-Sheet 2 an EN 60 F 2 Pi M 0') co P Fig; 3

ch M, H. E. AAMS fi a PUMP'ASSEMBLY Filed Sept. 19, 1945 '3 Sheets-Sheet s an Mn. 14, I a

lpumps, which causes vapor lock and pump failure.

The present invention relates to a pumpin unit and is an improvement on the general typ of pumping unit shown, described and broadly claimed in my copending application Serial No.

658,471, filed March 30, 1946. One object of the present invention is the provision of such a unit combining the characteristics of a self-priming centrifugal pump with a positive type rotary pump to give high capacity, vapor-free delivery of liquid fuel at low pressure and also to give low and intermediate capacity delivery of liquid fuel at high pressure when required. Such a pumping unit is particularly useful in connection with aircraft engines requiring high performance and employing atomizing fuel nozzles for either reciprocating type engines or for revolving gas turbine driven engines and/or jet propulsion. It

may, however, be used on other applications requiring similar performance and this invention is not intended to be restricted to this particular field.

A typical application of the pumping unit of the present invention is that of the newly devel oped art of Jet propulsion. Gas turbines employed in this type of propulsion require fuel to be delivered to the atomizing burner nozzles at relatively high pressure such as 300 to 1000 p. s. i. For this purpose, high pressure fuel pumps are normally employed, these pumps being of the gear or piston type or of multi-stage ,centrifugal'type,

as exemplified in my Patent No. 2,438,104. Incorporated with the main fuel pump is a systern of by-pass or throttle control which automatically varies the amount of fuel required by the engine to maintain its desired speed over varying altitudes. It is a characteristic ofthis type of propulsion that the fuel requirements decrease with the altitude and unless the fuel is automatically reduced in proportion to the altitude, there is danger of the engine burning up from over-speeding and over-heating. The main engine fuel pump and its control therefore per-' form a vital function in the successful operation of the airplane and any failure in either the fuel pump or its control would result in possible loss of the airplane.

These jet propelled. units are also equipped to burn almost any type of fuel including highly volatile. high octane gasoline fuels principally used on reciprocating type engines. The use of such highly volatile fuel subjects the to additional diiiiculty because of the non-lubricating qualities of the gasoline, which tends to wear out the fuel pump, and also because'of the vaporization in the fuel suction lines to these fuel system in my Patent No.2,46i,865 have been quite successfully used. These centrifugal type fuel booster pumps are onl capable of low pressure delivery, which is sufficient to overcome the possible vapor lock formation in the-fuel lines. It is highly desirable that such pumps be capable of delivering fuel under high pressure conditions upon emergency. as for example, in case of failure of either the main .engineffuel pump or its control. g

In accordance with my invention, I include new and improved means for handling the large capacity requirement at low pressure for the purpose of pressurizing the main fuel lines to prevent vapor lock, and also include pumping means which automatically or. manually come into acdeliver fuel against pressures up to 350 p. s. i.

and higher. The vane pump also serves as additional scavenging means to aid in priming the centrifugal pump.

Various other features and advantages. of the invention will be apparent from the following particular description and from an inspection of the accompanying drawings, in which:

Fig. l is a side view of an embodiment of thisinvention in connection with a mounting on the bottom wall of a fuel tank;

Fig. 21s the bottom plan view of the pump;

Fig. 3 is a cross-sectional view taken along line 3+3 ofFig .2; I

Fig. 4 is a cross-sectional view taken along the lines 4il of Fig. 2 with the conduits shown in Fig. 5 superimposed diagrammatically; and

Fig. 5 is a diagrammatic sectional view of the pump unit of the present invention, said sectional view being distorted from the actual relationship of the parts indicated in Figs. 1 to 4 in order to show more clearly the relationship between the passages and the different pump units.

Referring to the drawingsfthere is shown a fuel tank it having a wall H such as a bottom wall with an opening 12 through which the pump unit of the present invention passes. This pump unit comprises a body ll having a flange ll by which said unit is sealably bolted or otherwise fastened by a leak-proof connection to the bottom tank wall ll, so that the tank opening I2 is sealed. The pump unit is shown including three sections l3, l5 and I6 bolted or otherwise fastened together, and surmounted by an electric motor l1 adapted to drive a centrifugal booster pump It, a liquid ring type pump it for removing the vapor from the fuel in said booster, and a rotary vane type fuel pump 20. For driving these different pumps from the motor H, the motor shaft 2i is connected to the centrifugal impeller pump shaft 22 by a flexible coupling 23, and a pinion 24 on said impeller pump shaft meshes with a gear 25 on the shaft 26 of the fuel pump 20.

The entire pump unit is of such a height as to be completely submerged in the fuel which is to be pumped from the fuel tank Ill. The fuel inlet to the centrifugal booster pump is is through a strainer 30. From this strainer inlet 30, the fuel is divided between an upper inlet chamber SI and a lower inlet chamber 32. The booster pump it has a double suction centrifugal impeller 33 with an upper eye 34 and a lower eye 35, the fuel flowing into these eyes from the inlet chambers 3| and 32 respectively.

In Fig. 5, the pump unit of Figs. 1-4 is shown diagrammatically, but is shown mounted on the side wall of the fuel tank, instead of on the bottom wall of said tank. However this showing in connection with a side wall mounting is made to indicate that the pump unit of Figs. 1-4 can be so mounted. In all other respects, the pump unit is similar to that of Figs. 1-4..

As shown diagrammatically in Fig. 5, the booster pump impeller 33 discharges into a volute 31, which in turn discharges into two branch passages 38 and 39. Under normal operating conditions, the main flow of the centrifugal pump is through the connection 38 through a discharge connection ll, and into a T-fltting 42 to a main high pressure fuel pump 43 on the outside of the fuel tank It. From this main fuel pump 43, the fuel passes under high pressure through a check valve N, and through a main fuel line 45 to the burner nozzles (not shown).

During the normal operation of the plane and the pump, there is an auxiliary amount of fuel discharged through the passage 39 into the inlet 41 of the vane fuel pump 20. This fuel is discharged from the vane pump through an outlet 50 into a conduit 51, and from there through a discharge connection 52 to a T-fltting 53. The two fittings 42 and 53 are interconnected by a by-pass line 54 having a valve 55 which is normally opened. The high pressure fuel delivered by the main fuel pump 43 to the line 45 is prevented from flowing back through the T-fltting 53 by a check valve 56.

The motor I! is completely enclosed by apressure-tight housing formed by an upper bell casting 51, an intermediate cylindrical casting 58 and the lower bell casting l6. Liquid-tight gasket joints are formed between these three castings in any well-known manner. The bell casting 16 includes a rotating sealing member 59, which is in sealing engagement with a stationary bearing ID. The motor is thus protected from the ingress of liquid fuel from the tank. It is provided with a breather connection, which is not shown, and with a seal drain connection II to drain of! any incipient leakage from the sealing member 59. There are also provided separate conduits (not shown) extending from 4. the inside of the motor I? to the lower end of the pump casing, which contain the motor electric leads.

The pump l8 serves to remove vapors from the fuel in the pump l8 when handling volatile fuels, such as aviation gasoline. For that purpose, the casing of the pump it is provided near the two inlets 3i and 35 thereof with annular gas collecting grooves 60 and 6|. The vapors collect in these annular grooves 60 and 6| by centripetal action, and are conducted into the inlet ports 82 and 63 of the liquid ring vapor removal pump 19 by means of the conduits 64, 85, 86 and 81. The general arrangement of the fuel booster pump l8 with the liquid ring vapor removal pump is shown in my Patent No. 2,461,865. The pump is discharges these vapors after compression through discharge ports 68 and 68 directly below the pinion 24 mounted on the pump shaft 22.

The liquid ring pump l9 discharges air, vapor and liquid upwardly along the pinion 24, and into a discharge chamber 13. The flowing of the fuel past the gears 24 and 25 effectively lubricates these gears. Ordinarily, gasoline would be ineffective for that purpose, because of its low lubricating properties. However, these gears 24 and 25 operate right in the gasoline and are lubricated effectively thereby, because of the high speed at which they operate, and because oi the effect of the admixture of air and vapor which is discharged thereagainst by the pump 19 as described. Also, the agitation resulting from the gears 24 and 25 results in their running practically in a pocket of vapor and air bubbles. the gears in this manner reduces the friction normally experienced when operating gears in a flooded condition.

The vapor and liquid are then discharged from the chamber 13 upwardly through ports ll into an annular chamber 15 surrounding the stator windings of the motor; II. From here the liquid passes through additional ports 16 into another chamber 11 surrounding the airtight casing 51 housing the commutator and brush riggin of the motor H. The air and vapor are discharged upwardly through the top opening 8| of an outer motor casing 82 where they rise to the surface of the fuel in the tank, and the liquid overflows through the top of the chamber 11 over the upper annular edge 83 of the outer motor casing 82.

By means of the construction described, advantage is taken of the liquid discharged from the liquid ring vapor removal pump H! as a means for effectively cooling the motor II. This liquid is forced around the heated portions of the motor l1, so that by conduction, it removes the heat from said motor, thus enabling the motor to operate at high eificlency and with minimum dimensions. by the expedients described, this cooling is more effective than air cooling. It should .be noted that the liquid cooling applied to the motor I! exists at all times as long as there is any liquid in the tank Ill, even though the liquid level in said tank may be below the level of the motor. In the case of the usual submerged fuel booster pump construction, the motor is not cooled by the liquid in the tank, if the level of the liquid in the tank drops below the level of the motor. Such an arrangement is generally satisfactory for small-powered motors, but where high input is The breaking up of the fluid around Since the motor I! is liquid-cooled advantageous to provide for a liquid cooling arrangement ofthe motor such as that of the present invention. This liquid cooling is obtained at no additional cost and power, since the discharge of liquid from the liquid ring vapor removal pump it is utilized for this purpose.

The motor if is equipped with internal stationary and rotating vanes (not shown) for the internal circulation of air through the field coils and armature to transmit further the heat from these parts to the side walls of the liquid-tight enclosure, which in turn transmits this heat to the circulated liquid by which the heat is carried away.

It should be noted that as a feature of the present invention, protection against vapor binding of the centrifugal pump it is additionally afforded by the arrangement of the vane type rotary pump it. As already indicated, the liquid ring vapor removal pump it operates to clear of gas and vapor the suction side of the centrifugal volute in the pump i t. This arrangement is effec- -tive in maintaining vapor in bubble-free dis charge from the centrifugal pump it when handling efiervescing liquids, such as volatile aviation gasoline. Under extreme conditions, such as momentary uncovering of the suction, slopping, etc., the centrifugal pump it is liable to lose its prime. The liquidring pump it will prime the centrifugal pump upon return of liquid to the centrifugal pump suction. However, in accordance with the present invention, the 'repriming is speeded up and aided by the action of the positive displacement rotary vane pump it. because it exerts a continuous suction on the top of the volute at or centrifugal pump discharge 39, and therefore serves to constantly withdraw any gases or vapors collecting at this point. Thus, with the arrangement of the present invention, the centrifugal pump it is primed both from its suction side and its discharge side.

The vane pump it is in staged relationship with the centrifugal pump it for primary use as an emergency high pressure fuel pump. This vane pump 263 comprises a casing at having a cylindrical hero iii in concentric relationship with respect to the pump shaft 26, and a rotor 92 affixed to said shaft. The vane pump Ed is of the sliding vane type having four varies as arranged in quadrant relationship, with each set of two diametrically opposed vanes sliding in slots Ed in the rotor 92. In the central portion of the rotor $2 is located a pin 95, which maintains each opposite pair of blades in close proximity to the wall of the cylindrical bore at in the casing 99. This is a general type of vane pump pump welliznown per se. There are many variations of this general type of positive displacement rotary pump, and I do not wish to be limited to this specific rotary pump structure.

The vane pump 2d is driven by means of the gear 25 keyed to the motor shaft 26, this gear 25 being in turn driven by the pinion 25 from the main pump shaft 22, as already described.

speed is increased to afford higher differential pressure across the pump, its pumping capacity tries to increase at the same proportionate rate. It soon reaches a point where it istrying to pump liquid faster than the liquid in the suction line can get into the displacement spaces through the suction port of the pump. At this stage in the pump operation, the suction caused by this greater displacement lowers the absolute pressure at the inlet to the pump to a point where it approaches or goes below the vapor pressure of the liquid it is handling. The pump, under these conditions, develops noise and loses liquid capacity and its pressure capability.

Pumps 2% of this nature have been used in the aircraft industry as fuel pumps for a long time, and their pressure has always been limited to around 35 p. s. i. differential and a speed of about 2500 R. P. M. Beyond this speed and pressure, the objectionable noise and rapid disintegration of the pump occurs. It has therefore never been envisaged to employ these units for higher pressure operations, such as 200 or 300 p. s. i. differential. Because of this limitation in the operation of the general vane type of rotary pump, in their stead there have been used gear pumps or piston type pumps which can operate at a low speed and at low capacity, and which can deliver the low viscosity liquids against the higher pressures required. Even with pumps of this type, however, they operate at higher pressures to better advantage with high viscosity liquids.

In accordance with my invention, I place the inlet of the conventional vane type rotary pump under pressure so as to enable it to operate at high speeds, and thus obtain high differential pressures, such as 300 p. s. i. and 3500 R. P. M. The pressurizing of the liquid on the inlet side of the rotary pump it prevents the cavitation normally experienced at these high speeds, and completely charges the inlet of the vane pump with liquid fuel below the vapor pressure point of the fuel.

The arrangement of the different pumps with their difieren-t controls has already been explained in connection with the diagrammatic construction shown in Fig. 5. It has been shown in connection with this arrangement, that under normal operation, the vane pump 2 is not doing any work, and is merely lay-passing a quantity of fuel around the circuit 39, El, 53, M and 62, while the centrifugal pump it is pumping through conduits it to 62.

Even should the control in the main fuel line or atomizer line it be shut off, the positive acting pump 2%? would not build up pressure while the valve 55 is fully open, because any fuel that could not pass through the fuel pump 83 because of a closed discharge line, would return through condult 38 back through conduit 39 to the suction till One characteristic of this type of positive rotary as pump N is that its operational range is limited by two general factors. When operating at low speed, the maximum pressure obtainable with this pump is low, because of the slippage past the blade clearances in the pump. As the pump rotationalspeed is increased, it is capable of higher pressure, because the increased speed allows less time interval for slippage past each vane or blade 93. The pump it byits inherent nature has a fixed displacement per revolution, and as the ll of the rotary vane pump 28. The pressure throughout all of these conduits would be essentially at the discharge pressure of the centrifugal pump it. The discharge pressure of the cen= trifugal pump it would not rise higher than its normal no-flow value, which in this case is approximately 30 p. s. 1., because of the centrifugal characteristics of this type of pump by which the maximum pressure is limited by the speed of rotation of the centrifugal pump impeller 33.

If, for any reason, there is a failure of the main high pressure fuel pump t3, or any of the controls coordinated with it, it would nevertheless, under these emergency conditions, be desirable to continue to furnish high pressure fuel to the nozzles in the main line 45. In accordance closed, all of the fiow through the positive vane type pump 20 is then forced to go through the check valve 56 and into the burner supply line 45. Any back flow into the centrifugal pump it or into the disabled main high pressure fuel pump 43 is prevented by the check valve 64.

By means of this arrangement, the vane type rotary pump 20 serves as an emergency main fuel pump operating like pump (53 to deliver fuel at high pressure to the burner supply line 45 as just described when the valve 55 is closed or partly closed. The control of the amount of delivery to the burner nozzles through the line 45 from the vane pump 20 can be effected by adjustment of valve 55. While this valve 55 is open, it by-passes some of the fuel delivered under high pressure by the vane pump 20 back to the suction side of this pump through connections 42, ll, 38 and 39. By the proper adjustment of valve 55, which may be done manually or by automatic means, such as the known barometric compensated relief valve, the required amounts of fuel may be fed by the pump 20 at the required pressure to the burner nozzles through the line 45.

As a protection against the overloading of the motor I! in cases where higher pressures should be encountered by the pumps than that for which they were primarily designed, a relief valve assembly Hill is provided. This valve assembly comprises a poppet type valve HH held on its seat I02 by an adiustable spring I03 so arranged that when the desired maximum relief point is reached in the discharge conduit 5|, the valve i0! will open and will cause the liquid to discharge back into the tank It in which the complete pump unit is located.

As many changes can be made in the above apparatus, and many apparently widely different embodiments of this invention can be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I have described what I believe to be the best embodiments of my invention. I do not wish, however, to be confined to the embodiments shown, but what I desire to cover by Letters Patout is set forth in the appended claims.

I claim:

1. In combination, a fuel feed line for an internal combustion unit, a pair of branch conduits connected into said line, a main fuel pump in one of said branch conduits, a check valve in said latter branch conduit on the discharge side of said main fuel pump permitting flow to said feed line from said latter branch conduit, but blocking flow in the opposite direction, a fuel booster pump having a branch discharge connection leading to the inlet of said main fuel pump, an emergency fuel pump having its discharge connecting into the other branch conduit, a check valve in said other branch conduit permitting flow to said feed line, from said other branch conduit, but blocking flow in the opposite direction, said fuel booster pump having another branch discharge connection connected into the inlet of said emergency fuel pump, a by-pass line between said branch conduits, and a valve in said by-pass line.

2. The combination as described in claim 1, in which said emergency fuel pump is of the rotary 8 vane type. and said fuel booster pump is of the centrifugal typ 3. In combination, a fuel feed line, a pair of branch conduits connected into said fuel feed line, a main fuel pump in one of said branch conduits, an emergency fuel pump having a discharge leading to the other of said branch conduits, said emergency fuel pump during normal operations of the main fuel pump being insufiicient to deliver fuel to said feed line at the required pressure, a fuel booster pump having two branch discharge connections, one of said branch connections leading to the inlet of said main fuel pump and the other to the inlet of said emergency fuel pump, and means for supplying to said line by the operation of said emergency pump, fuel at the required pressure to make up deflciency in said required pressure.

'4. The combination as described in claim 3, in which said emergency fuel pump is of the positive rotary displacement type.

,5. The combination as described in claim 3, inwhich said emergency fuel pump is of the rotary vane type.

6. The combination as described in claim 3, in which said fuel booster pump is of the centrifugal y -'i'. The combination as described in claim 3. in which said emergency fuel pump is of the rotary vane type, and said fuel booster pump'is lofthe centrifugal type.

8. The combination as described in claim 3, in

which said fuel booster pump has means for separating the gases from the fuel being pumped and collecting them near the inlet of said booster pump, and in which there is provided a gas removal pump for pumping the collected gases from said fuel booster pump.

9. The combination as described in claim 3, in

which said fuel booster pump is of the centrifugal type with an axial inlet and a peripheral volute discharge, and has an annular gas collecting chamber in its casing surrounding said inlet, and in which there is provided a gas removal pump for pumping the collected gases from said chamber. 10. The combination as described in claim 3, in which said fuel booster pump is of the centrifugal type with an axial inlet and a peripheral volute discharge, and ,has an annular gas collecting chamber in its casing surrounding said inlet, and in which there is provided a gas removal pump for pumping thecollected gases from said chamber, said emergency pump being of the rotary vane'type.

'11. In combination, a fuel feed line, a pair of branch conduits connected into said fuel feed line, a main fuel pump in one of said branch conduits, an emergency fuel pump having a discharge leading to the other of said branch conduits, a fuel booster pump having two branch discharge connections, one of said branch connections leading to the inlet of said main fuel pump and the other to the inlet of said emergency fuel pump, and means for controlling the amount of fuel admitted from the discharge of said emergency pump to said other branch conduit, whereby deficiencies in required pressure in said line may be made up by the operation of said emergency pump.

12. The combination as described in claim 11, in whichjsaid controlling means comprises a by pass line between the two branch conduits, and a valve in said by-pass line.

. 18. The combination as described in claim 11, a RCES CIT said ntmmng means is Pembl while. The following references are bf record in the aaoaaaa maintaining the speed of said'emergen'cy pump me of this patent:

substantially constant.

14. The combination as described in claim 11, 5 m STATES PAWS comprising a motor, and means for driving said Number Name Date emergency fuel pump and said fuel booster pump 2.0 4.133 Harding Dec. 10, 1935 from said motor at a predetermined substantially 2,1 1 Parker Feb. 6, 1940 constant speed ratio. 5 Curtis Sept. 28, 1943 mm ms 2,390,204 Curtis new. 1945 Gm l 3,414,158 Mock Jan. 14, 1947 

